C++ 解法, 执行用时: 0ms, 内存消耗: 8552KB, 提交时间: 2015-03-17

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *deleteDuplicates(ListNode *head) {
        ListNode *p;
        ListNode *q;
        p = head;
        while (p!=NULL && p->next!=NULL)
        {
            if (p->val == p->next->val)
            {
                ListNode *temp;
                temp = p->next;
                p->next = temp->next;
                free(temp);
            }
            else
            {
            	p = p->next;    
            }
        }
        return head;
    }
};

C++ 解法, 执行用时: 0ms, 内存消耗: 8684KB, 提交时间: 2015-03-17

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *deleteDuplicates(ListNode *head) {
        ListNode *cur=head,*nxt;
        int val;
        while(cur){
            val=cur->val;
            nxt=cur->next;
            while(nxt&&nxt->val==val) nxt=nxt->next;
            cur->next=nxt;
            cur=nxt;
        }
        return head;
    }
};

C++ 解法, 执行用时: 0ms, 内存消耗: 8684KB, 提交时间: 2015-03-17

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *deleteDuplicates(ListNode *head){
        /*保存头指针*/
        ListNode* root = head;

        while(head != NULL)
        {
            /*下一节点存在，且当前节点和下一节点的值重复*/
            while(head->next != NULL && head->val == head->next->val)
            {
                head->next = head->next->next;
            }
            head = head->next;
        }
        return root;
    }
};

C++ 解法, 执行用时: 2ms, 内存消耗: 332KB, 提交时间: 2021-05-12

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */

class Solution {
public:
    /**
     * 
     * @param head ListNode类 
     * @return ListNode类
     */
    ListNode* deleteDuplicates(ListNode* head) {
        // write code here
        if(head == NULL)
            return head;
        ListNode* temp = head;
        while(temp->next!=NULL){
            if(temp->val == temp->next->val){
                temp->next = temp->next->next;
            }
            else{
                temp = temp->next;
            }
        }
        return head;
        
        
    }
};

C++ 解法, 执行用时: 2ms, 内存消耗: 332KB, 提交时间: 2020-11-23

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */

class Solution {
public:
    /**
     * 
     * @param head ListNode类 
     * @return ListNode类
     */
    ListNode* deleteDuplicates(ListNode* head) {
        // write code here
        if(head==NULL)
        {
            return NULL;
        }
        for(ListNode* i=head;i!=NULL;i=i->next)
        {
            for(ListNode* j=i->next;j!=NULL;j=j->next)
            {
                if(i->val==j->val)
                {
                    i->next=j->next;
                }
            }
        }
        return head;
    }
};